I. Field of the Invention
The present invention relates to a self-cleaning shower nozzle system for use in the paper making industry. More specifically, the present invention allows for more effective use and recycling of white water for both high and low pressure fan and needle showers.
II. Prior Art
The paper making industry has for many years used fresh water in their showers with satisfactory results in both quality and cost of their paper. High and low pressure showers are required in the paper making industry to assure that the paper forming fabrics are lubricated and cleansed on a continuous basis. The quality of the paper is controlled by the smooth and clean travel of the forming fabrics through the paper machine. It is necessary that water is sprayed continuously on these fabrics, therefore ,shower plugging is a critical problem. Our self cleaning shower system eliminates this problem.
However, due to the ever-increasing costs of energy and mill effluent treatment, paper mills are recycling white water at an ever-increasing rate. (White water is a combination of fiber, chemicals, and water which forms the basic element of paper making.) The recycling of white water causes the showers on the paper machines to plug. This creates a need for an automatic, remotely operated, and safe method of self-cleaning.
In the past, attempts have been made to provide for a self cleaning shower nozzle. These attempts have been limited in success and in some cases caused further problems.
One approach to solving the problem of shower plugging is the use of an internal brush rotating inside the shower manifold. By either a back and forth or rotating motion, the brush moves over the nozzle orifice and wipes away any fiber or solids plugging the opening. This action supposedly removes any build up. Practically, however, the motion has a tendency to drive fiber or solids into the orifice rather then wiping away this build up. There are no apparent patents for this type of system although widely used in the paper industry. This system is supplied by various companies including Spraying Systems Co. of Illinois.
A second method involves a retracting piston which opens the orifice when internal manifold pressures are relieved or reduced. This allows a trickle of white water to flush the enlarged opening before closing when internal pressure is resumed. The problems in this method are twofold. One, when the pressure is low or off and white water is at a trickle, the build up of solids will not flush away. The piston, when pressurized, will jam on its return stroke and give a distorted nozzle spray pattern. Secondly, fibers have a tendency to plug moving parts in a short period of time, therefore limiting the effect of the piston motion. There are no apparent patents for this system and this system is of limited use in the paper industry. This system is supplied by various companies including Spraying Systems Co. of Illinois.
A variety of other water spray nozzles have been proposed, such as disclosed in U.S. Pat. No. 5,119,991 in which a nozzle assembly includes a sleeve, nozzle having an interior opening and slidable within the sleeve and a plunger that enters the interior opening of the nozzle. When the nozzle is slid within the sleeve, the plunger co-acts with the nozzle to clean any foreign substances present within the nozzle and remove a clog in the nozzle. The plunger, rather than remove debris, can further the problem by jamming fibers and solids into the orifice.
U.S. Pat. No. 2,117,647 in which a jet cleaning device is shown for a nozzle having an axially displaced plunger movable into the nozzle by the application of a force on the plunger. The force on the plunger opposes a biasing force applied by a spring that is interposed between the nozzle and the plunger. Cleaning of the nozzle is accomplished by first pushing the plunger into the nozzle and then rotating the plunger. Release of the force applied against the plunger causes the plunger to be withdrawn from the nozzle due to the biasing force of the spring. A disadvantage of this device is that cleaning involves a two step process of pushing the plunger within the nozzle and then rotating the plunger within the nozzle.
U.S. Pat. No. 3,474,968 discloses a self-cleaning nozzle that is axially movable into and out of the housing supporting the nozzle. The pressure of the fluid that is discharged from the nozzle controls the movement of the nozzle into and out of the housing. The nozzle is a generally hollow, cylindrical body having a sidewall defining one or more slits. The fluid to be discharged from the nozzle enters the nozzle through the slits and exits through an open end of the nozzle. A spider member, having projections that extend into the slits of the nozzle, is attached to the housing so as the nozzle moves into and out of the housing, any foreign substances that may be caught within the slits of the nozzle will be cleared.
While there are some merits to the approaches mentioned above, none fulfill the purposes of the present invention.